The present invention is directed to a light waveguide cable composed of at least one light waveguide, a light waveguide bundle or a light waveguide ribbon having a cable cladding of plastic for utilization on a line cable of a high-tension system.
WO 96/38892 discloses a method for the installation of a light waveguide cable on an overhead high-tension line. The light waveguide cable, for example an optical overhead cable, is secured with the assistance of at least one cable strapped along a high-tension cable, whereby the cable strap is wrapped around the high-tension cable and the light waveguide cable with a wrapping, machine. What is referred to as an ADL cable (ADL=All-Dielectric) is especially suited for this purpose. It is composed of a tubular envelope into which the light waveguide, light waveguide ribbon or light waveguide bundle are loosely introduced. A cable cladding of plastic is located thereover and a gel-like substance can also be introduced into the interior of the tubular envelope, whereby the mobility of the light waveguide is preserved.
EP 0 321 278 A1 discloses a cable combination composed of an optical cable and an electrical conductor, for example a high-tension cable. The optical cable is helically wound around the electrical conductor. The optical cable is composed of a tubular envelope in which one or more light waveguides or light waveguide ribbons are introduced, so that they can move therein. A gel-like filling compound can also be provided. The envelope is surrounded with a tensile cladding and, potentially, with a further sheath of heat-resistant material.
Polyolefines, such as polyethylene or medium density (MDPE), high-density polyethylene (HDPE) or polypropylene (PP), are usually employed as materials for enveloping optical cables. These materials are potentially ultraviolet-stabilized with the addition of lampblack. Such envelopes are adequate, for example, for mounting at or, respectively, on phase cables of high-tension systems up to a voltage value of approximately 30 kV. Given higher voltages, however, Corona discharges occur that can lead to the premature destruction of the envelope or, respectively, the cable cladding.
The object of the present invention is to create a light waveguide cable whose cable cladding is protected against destruction by Corona discharges. This object is achieved with a light waveguide cable of a species initially cited in that a Corona-resistant layer is applied on the cable cladding. An optical cable having a known structure is cladded with a Corona resistant skin layer according to the present invention, so that the occurring Corona discharges can no longer destroy the cable cladding. The risk of premature destruction of the cable claddingy composed of the previously standard plastic materials is thereby prevented. High-temperature thermoplastics, such as, for example, fluoropolymers, silicones and polyimides as well as copolymers of these material compounds are particularly suited for such a skin layer. The necessary layer thickness for the skin layer amounts to 100 xcexcm through 2 mm. This skin layer is applied as a surface-covering on the cable cladding, preferably by coextrusion during the manufacturing of the optical cable.
Other advantages and features of the invention will be readily apparent from the following description of the preferred embodiments, the drawing and claims.